Alfvén Wave-Driven Proto-Neutron Star Winds And R-Process Nucleosynthesis

We propose magnetic proto-neutron star (PNS) winds driven by Alfvén waves as well as the neutrino heating as an appropriate site for the r-process nucleosynthesis. Alfvén waves excited by surface motions of a PNS propagate outwardly, and they heat and accelerate the wind by dissipation. Compared with the wind purely driven by the neutrino heating, larger entropy per baryon and shorter dynamical time scale are achieved, which favors the r-process. We study reasonable cases that a wave amplitude is 10% of Alfvén speed at the surface to find that a PNS with surface field strength, & 5 × 10G, gives suitable wind properties for the r-process, provided that dissipation length of the wave is at most ∼ 10 times of the PNS radius. We also compare properties of transcritical and subcritical winds in light of the r-process. We finally discuss possibilities of detections of γ-rays from radioactive nuclei and absorption lines due to Ba in supernova remnants which possess magnetars. Subject headings: magnetic field – nuclear reactions, nucleosynthesis, abundances – plasmas – stars:neutron – supernovae:general – waves